The thermal pulse flow meter described in U.S. Pat. No. 4,491,024 to Miller, Jr. and in U.S. Pat. Nos. 4,532,811 and 4,628,743 to Miller, Jr. et al. was an advancement in the art of flow measurement because, for example, it used no moving parts and was extremely accurate.
The gist of the thermal pulse flow meter is that an upstream thermal probe located in the flow cell of the flow meter is pulse heated to thereby generate a thermal pulse in the fluid flowing through the flow cell. A thermal probe located downstream in the flow cell then detects the passage of the thermal pulse. The time period between successive thermal pulses is a mathematical function of the flow rate of the fluid flowing through the flow cell. The commercial thermal pulse flow meter sold by the Molytek Corporation, also incorporates a temperature compensation thermistor probe to determine the temperature of the fluid flowing through the cell. The above mentioned patents are fully incorporated herein by reference.
When used, for example, for the flow measurement of sterile fluids for biological applications, the flow cell and thermal probes of the thermal pulse flow meter required cleaning and sterilization before use. The present invention is a solution to this and similar problems.